Co-site interference between wideband receiver and switching power supply

This technique was developed to support a technical risk analysis to determine the likelihood of interference between a noisy RF source and a sensitive radio receiver. This paper analyses the worst case conditions for co-site radiated interference between a switched mode power supply certified to MIL-STD-461B and a wideband radio receiver system. The analysis suggests that despite the application of MIL-STD-461 and a RF isolation sub-chassis for the sensitive RF receiver elements, there remains a risk that the system noise floor and hence the minimum discernible signal level will be affected by the nearby high power switched mode power supply. This paper only addresses theoretical performance and the result highlights the need for testing of the components to identify whether further interference mitigation measures are required as part of the installation package. Unfortunately, neither candidate receiver or power supply elements were available for testing prior to this drafting of this paper. This paper discusses the radiated emissions aspects of MIL-STD-461. The conducted emissions (passed along the power and control lines) are likely to be more significant than radiated emissions, but may be manageable through the suitable application of in-line filters. Careful consideration should also be given to radiated emissions from the wires leading into the power supply. These lines may also require filtering.